Dimensional Weight Calculator
Whether a carrier will bill this parcel by its size or by its scale weight, and by how much.
Carriers charge for the greater of the actual weight and the dimensional weight — the volume of the box divided by a divisor the carrier sets.
How the dimensional weight calculator works
Carriers charge for the greater of the actual weight and the dimensional weight — the volume of the box divided by a divisor the carrier sets. A large, light parcel is billed on size; a dense one on the scales.
The divisor decides everything: 5,000 (cubic centimetres to kilograms) is the usual express and international figure, 6,000 is common for domestic parcel services, and US carriers use 139 cubic inches per pound on daily rates. Pick the method the carrier quotes; the dimensions are entered in that method's unit.
Formula: dim weight = L × W × H ÷ divisor; billable = max(actual, dim weight)
Worked examples
| Inputs | Billable weight | Note |
|---|---|---|
| Light and bulky | 4.8 kg | 24,000 cm³ ÷ 5,000 = 4.8 kg beats 3 kg on the scales |
| US daily rate | 27.63 lb | 3,840 in³ ÷ 139 = 27.63 lb |
| Dense carton | 6 kg | 4 kg by size, 6 kg on the scales — billed at 6 kg |
FAQFrequently asked questions
What is dimensional weight?
A weight the carrier derives from the size of the parcel: length × width × height divided by a divisor the carrier publishes. It is compared with the actual weight and the greater of the two is billed.
Which divisor should I use?
The one on the rate card you are billed under. Express and international services commonly use 5,000 with centimetres; many domestic services use 6,000; US carriers quote 139 cubic inches per pound on daily rates and 166 on retail rates. Two carriers can bill the same box differently.
How do I reduce a size-based charge?
Shrink the box. Dimensional weight scales with volume, so trimming 2 cm from each side of a 40 × 30 × 20 cm carton removes about a quarter of its volume. Less void fill, right-sized packaging and folding soft goods flat all help.
Do carriers round the dimensions?
Most round each dimension up to the next whole centimetre or inch before multiplying, and some round the final weight up to the next half or whole unit. This calculator uses the figures as entered; treat a result that sits just under a rounding step as at risk.
Where these figures come from
- APICS / ASCM — inventory management terminology — the turnover, safety stock and reorder point definitions used here
- Australian Competition and Consumer Commission — the Australian consumer law regulator
Last checked: September 2026. These are standard retail and inventory-management definitions.